Question: $5.4 \times 3.72 = $
Solution: ${5}$ ${4}$ ${3}$ ${7}$ ${2}$ ${\times\vphantom{0}}$ ${.}$ ${.}$ ${0.4}\times {0.02}= {0.008}$ ${8}$ ${5}\times {0.02}= {0.10}$ ${0}$ ${1}$ ${0.4}\times {0.7}= {0.28}$ ${8}$ ${0}$ ${5}\times {0.7}+C{0.2}= {3.7}$ ${7}$ ${3}$ ${0.4}\times {3}= {1.2}$ ${2}$ ${0}$ ${0}$ ${5}\times {3}+C{1}= {16}$ ${6}$ ${1}$ ${+\vphantom{0}}$ ${2}$ ${0}$ ${0}$ ${8}$ ${8}$ ${+\vphantom{0}}$ ${2}$ ${0}$ ${0}$ ${8}$ ${8}$ ${.}$ The top number has $1$ digit to the right of the decimal. The bottom number has $2$ digits to the right of the decimal. The product has $1+2=3$ digits to the right of the decimal. $5.40 \times 3.72 = 20.088$